Monitoring cameras are commonly used to monitor building, roads, shops and various other places. In particular, cameras are often used to monitor scenes to allow automatic detection or tracking of events in the form of presence of motion or presence of an object of a specific type. Such monitoring cameras can be used both indoors and outdoors. A monitoring camera mounted outdoors is sometimes exposed to harsh weather conditions such as wind, snow and rain. A common problem which occurs when rain drops are present in the view of the camera is that these by mistake trigger alarms. This typically happens when the camera is unable to separate a small object close by, such as a rain drop trickling down the cover glass of the camera lens, from a larger object more far away, such as a car or a person moving at a distance from the camera.
Another problem which may occur when rain drops or other drops of water (or other fluids) are present on a cover glass of the camera is that the camera's focus lens system will focus on the rain drops, instead of on more interesting objects in the monitored environment. These “real” objects may then become blurry and difficult to see for an operator.
Different solutions have been presented in this area, such as window wipers that clear the water from the camera cover glass. However, there is still room for improvement in this area.